Switch



March 25, 1941. N. c. SCHELLENGER 2,235,902

swI'rcH Original Filed June 6, 1936 2 Sheets-Sheet 1 March 25, 1941. N. c. SCHELLEZNGER SWITCH Original Filed June 6, 1936 2 Sheets-Shqet 2 NEWTUT? C4. EEfZE/ETY ET" Patented Mar. 25, 1941 UNITED STATES PATENT OFFICE 24, mm Divided and this application October 14, 1939, BerlalNo. 299,518 a r 4 mains.

This invention relates to switches and more particularly to improvements in snap switches of the type operated by a cam actuated spring toggle. The subject matter or this application 5 is a division or the copending application or New- C. Schellenger, Serial No. 83,963, iiled June 6, 1936, for Switches, now Patent No. 2,177,284, issued October 24, 1939.

Switches of this type are particularly useful for controlling electrical circuits of radio receiving sets which feature compactness.

Accordingly, one of the objects of invention to provide an improved snap switch of the character described, which is compact in design, thereby. requiring very little space for its installation in small radio receivers.

While switches of this type may be installed separately, it is the practice, in instances where little space is available, to mount the switch on 21]? some other control actuated from the panel of the radio such as a volume or variable resistance control.

When so combined, the actuating shaft of the variable resistance or other control is provided 5 with an arm or disc having 9. lug movable in an arcuate path and adapted for transient engagemeut with portions of the switch cam lying in the path of the lug so that actuation of the shaft transiently engages the lug with the cam and actuates the switch to either on or oil? position.

In some instances in combinations oi this type the spaced arms of the switch cam, which provide the abutments engaged by the driving lug, faced inwardly, but in the more recent developments 135 the cam arms pointed outwardly away from the axis of the actuating shaft so the driving lug passed between the cam and the wall or the control housing. The housing thus had to be large enough to accommodate the lug and 49 the outwardly directed arms.

While this latter construction would permit smooth and easy operation oi the switch it the arms of the cam were long enough to provide the proper leverage and a round pin was used as the 45 driving lug, the constantly growing demand for reduction in size of all radio controls decreed a construction wherein the arms oi the cam were shortened and as a result thereoi the point of iorce application was brought so to the axis so of the cam that actuation of the switch was diuicult.

suggested reversal of the cam so that its arms would face inwardly toward axis or the actuating shaft. Such or the cam- 55 permitted the use of longer arms in the (CL Mill-67) leverage necessary for easy cam actuation and also made possible the primary object namely. reduction in size the control housing. The actuating lug in this instance, of course, moved on an are between the cam and the actuating 5 shaft.

This construction also made use of a round pin as the driving lug to insure smoothness of operation; but because of the arcuate path or travel or the pin with relation to the position of the cam arms, initial contact between the pin and the arms was at a point spaced radially a. substantial distance in from the outer ends of the arms and close to the cam pivot axis thereby losing much of the available leverage. The advantages sought to be gained from reversal of the cam was thus substantially nullified as a relatively large initial i'orce was still required to actuate the switch.

This construction, therefore, was also objectionable for it achieved compactness only at the expense of easy operation.

The substitution of a driving lug having fiat sides substantially radial to the axis of the actuating shaft, for the round driving pin as disclosed in the copending application of Newton C. Schellenger, Serial No. 83,963, overcame the objection of high initial operating force but lacked the smoothness of the round driving pin, and in addition was subject to the possibility of a reduction in leverage during actuation of the switch cam.

with these objections to past switch constructions of the character described in mind, the present invention has as its specific object to provide an improved switch cam construction so combined with a flat driving lug as to insure the attainment of all of the features sought namely, smooth operation and maximum leverage to reduce the iorce required for opening and closing the switch to a minimum, without sacrificing compactness.

This objective is achieved through the use of an actuating cam having its arms directed toward each other and rounded at their extremities, with the space between the arms undercut to define a reentrant recess large enough to acoommodate the flat driving lug and so shaped as to insure the transmission of driving force from the lug to the cam only through engagement between the hat sides of the lug and the rounded ends of the arms. The point of force application is thus maintained at substantially constant maxradlal distance from the cam axis. a

with the above and other objects in view which will appear as the description proceeds, this invention resides in the novel construction, combination and arrangement of parts substantially as hereinafter described, and more particularly defined by the appended claims, it being understood that such changes in the precise embodiment oi the hereindisclosed invention may be made as come within the scope of the claims.

The accompanying drawings illustrate one complete example of the physical embodiment-of the invention constructed in accordance with the best mode so far devised for the practical application of the principles thereof, and in which:

Figure 1 is a sectional view of a toggle type snap switch illustrating the compact arrangement of the parts thereof Figure 2 is a sectional view illustrating the position of the cam with the switch in open position;

Figure 3 is a view similar to Figure 2 illustrating the position of the cam with the switch in closed position;

Figure 4 is a transverse sectional view taken on the line 3-6 of Figure 1;

Figure 5 is a perspective view of the improved switch cam per se;

Figures 6, 7, 8 and 9 are diagrammatic plan views showing progressively the engagement of the agtuating lug with the switch cam; and

Figure 10 is a perspective view of the shaft carried switch actuating member showing the lug which engages the cam to actuate the switch.

Referring now particularly to the accompanying drawings, in which like numerals indicate like Parts, the switch, indicated generally by the numeral I0, is provided with a shallow cylindrical housing ll which, in the present instance, is shown as supported from the housing of a variable resistance unit 12. It is to be understood, however, that any suitable shaft operated control may be used in combination with the switch for the purpose of operating the same or the switch may be mounted directly on the panel and provided with a separate operating shaft.

When the switch III is mounted on the rear of the variable resistance unit, as shown in Figure 1, the switch housing II is provided with a plurality of ears l3 which are inserted through perforations in the rear wall ll of the variable resistance housing and are turned over against the underside thereof to firmly secure the switch housing in place upon the variable resistance housing.

The switch comprises a base i5-of insulating material held in the bottom of the switch housing between an inturned flange IS on the outer edge of the housing and by inturned lugs I! struck from the side wall of the housing and engaged with the inner face of the base.

The base I5 is notched, as at ii, to engage an inwardly bent portion I 9 of the housing II, as shown in Figures 2 and 3. The inwardly bent or indented portion IQ of the switch housing positively locates the base with respect to the housing H and also serves as a stop for the switch cam, as will be hereinafter more fully described. I

A pivot pin 20 is anchored in the base l5 near the edge thereof and pivotally mounts a switch arm 2-l between an enlargement 22 on the pin and a flange 23 thereon adjacent to the base so that the switchv arm is parallel to but spaced from the base.

As is customary in constructions of this type, the switch arm is provided with a keyhole type opening to permit assembly thereof on the pivot pin between the enlargement 22 and the flange 23.

The movable or bridging contactor 24 is positioned between the switch arm 2| and the base II and has a driving connection with the switch arm so that pivotal motion of the switch arm carries the movable contactor intoand out of engagement with a pair of spaced stationary contacts 25 and 26 which project inwardly from the inner face of the base. To drivingly connect the movable contactor with the switch arm, the movable contactor 24 is provided with an upturned pivot lug 21 which fits in an opening 28 in the switch arm.

The opening 28 is larger than the lug 2'! so that the lug fits substantially loosely therein and allows the contactor a degree of pivotal motion with respect to the switch arm. The contactor is also provided with a lug 29 engageable in a notch 33 in the switch arm to positively limit the pivotal motion between the switch arm and the contactor.

The switch can 32 of this invention comprises a U-shaped metal member, whose legs 33 and 34 are provided with aligned openings 33' and 34' by which the cam is mounted on the pin 20 for pivotal motion thereon. The legs 33 and 34 are spaced apart sufliciently so as to provide a double bearing for the cam on the pivot pin and permit free operation without danger of binding.

The leg 34 of the cam which is disposed adjacent to the switch arm 2| is provided with a perforation 35 to receive one end of a toggle spring 36. The other end of the toggle spring projects through an opening in the switch arm and connects the switch arm and contactor with the cam so that pivotal motion of the cam in either direction actuates the toggle and snaps the contactor into or out of bridging engagement with the stationary contacts 25 and 26. Such pivotal motion of the cam is limited by the engagement of stop lugs 33 on the leg 34 with either side of the indented portion of the housing wall I9.

The cam 32 is of such proportions that its leg 33 projects from the open end of the switch housing; and when the switch is associated with a variable resistance unit, as illustrated in the drawings, the leg 33 of the cam projects through an opening I 4' in the rear wall of the variable resistance housing to lie within the housing.

The edge of this leg 33 of the cam which faces the axis of the switch housing has a reentrant recess or c shaped opening 32' therein extending to a point closely adjacent to the pivot hole. The stock of the leg 33 surrounding this recess thus provides two approaching arms or horns 39 and I the extremities of which are rounded to serve as a pair of spaced undercut abutments.

The cam is held in such a position by the spring toggle that the extremity or abutment of either one or the other of its arms or horns lies in the arcuate path of a flat blade-like lug ll struck up from an actuating disc 42 drivingly connected with the inner end of the variable resistance operating shaft 43. The opposite flat sides of the lug are substantially radial to the axis of the shaft 43.

The manner in which the lug 4| is brought into engagement with either one or the other of the abutments provided by the arms 39 and I0 is illustrated progressively in Figures 6 to 9, inelusive.

with the parts in the positions illustrated in Figure 6, the switch is open and the cam Ill lies in the path of the driving lug. Closing of the switch is effected by turning the shaft 13 in a direction to move the lug ll clockwise (as viewed in Figures 6 to 9). This means that the shaft 43 of the variable resistance unit must be rotated in a counterclockwise direction when viewed from the exposed end of the shaft.

As such arcuate movement of the lug ll proceeds it enters the recess 32' and engages its leading flat sidewith the horn I, as shown in Figure 7, at a point near the extremity of the arm so as to insure maximum leverage for initiating cam actuation. Continued motion of the driving lug carries the cam toward dead center of the toggle which position is illustrated in Figure 8. It is to be noted with the cam in this position, the point at which force is being applied to the cam is at the extremity of the arm ll and as will be readily apparent, the point of engagement between the lug and arm remains substantially the same maximum radial distance from the cam pivot axis throughout the entire period of engagement. This is extremely important as it is only by maintaining the point of force application on the cam at a maximum distance from the cam center that proper leverage for easy actuation of the cam is obtained.

It is further seen from Figure 8 that the shape of the recess 32' and consequently the shape of the inner edges of the arms I! and ll. and the radial length of the lug is such as to preclude the possibility of any rough edge portion of the lug ll contacting or digging into the arms. Contact is always between the medial portion of the flat sides of the lug and the rounded extremities of the arms.

A slight clockwise motion of the lug from its position shown in Figure 8 releases the toggle to snap the switch closed and bring the cam to its position shown in Figure 9. This closed position of the switch is also illustrated in Figure 3.

The arm 40 is now out of the path of the lug ti, so that shaft rotation can be continued if necessary, and the cam arm 39 is in the path of the lug to be engaged thereby upon opposite rotation of the shaft.

In this respect it is pointed out that the distance between the arms or horns 39 and 40 is great enough to make the switch trip free, i. e., it permits final movement of the cam without interference from the lug H, and entirely independently of the speed of movement of the operating shaft.

Rotation of the lug 4| in a counterclockwise direction (with respect to Figures ,6 to 9) to open the switch engages the lug with the arm or horn iii to actuate the cam in the manner described, but in the reverse direction.

The cooperation between the rounded extremities of the arms or horns 39 and 40 and the fiat substantially radial faces of the lug 4| reduces friction during cam actuation to a minimum, which is important in view of the reduced radial distance between the actuating shaft axis and the point of lug engagement with the cam arms. necessitated by the demand for compactness.

The use of a flat actuating lug is preferable to the pin type actuator as it enables its point of engagement with the rounded extremities of the cam arms to be maintained a maximum distance from the cam pivot axis during switch actuation. Another advantage resulting from the use of a flat actuating lug is that the lug may be formed simultaneously with the stamping of the disc 42, which is obviously less costly than riveting a pin to the disc.

Furthermore, the flat blade-like lug may be formed on the disc 42 at the extreme edge thereof to utilize the whole radius of the disc or its equivalent. This is impossible when using a pin type lug as the pin must be spaced inwardly from the edge of the carrying disc to enable attachment thereto'and to provide the necessary die strength.

While the lug 4| may have very rough and sharp edges as a result of the stamping operation, this possibility can not in anywise affect the smooth operation of the switch for, as noted hereinbefore, the shape and relative proportions ofthe driving lug and the cam arms precludes any but flat surface engagement of the lug with the rounded extremities of the arms. Wear and friction on the engaging parts of the cam and lug are .thus held to a minimum.

It is to be understood that the combination of a flat blade-like driving lug and cam arm's having rounded undercut extremities insures smoothness and ease of operation regardless of whether the cam arms point inwardly,-as shown. or outwardly away from the axis of the switch housing.

From the foregoing description taken in con-' nection with the accompanying drawings, it will be readily apparent that the design and arrangement of the actuating blade and switch cam of this invention enables a compactness of design heretofore impossible in controls of this type, and that smoothness and ease of operation is insured by the novel cooperation of these parts.

What I claim as my invention is:

1. In an electric snap switch of the character described: a movable contactor; a spring toggle for snapping the contactor from one position to another, said spring toggle including a cam member mounted to oscillate about a fixed axis between predetermined limits, said cam member having a part extending radially from its axis of oscillation, the outer edge of which has a c-shaped opening therein to provide two spaced undercut abutments the extremities of which are rounded; and a flat blade-like actuating lug movable flatwise in an arcuate path which enters the c-shaped opening for transient engagement with the rounded extremity of one of said abutments to swing the cam member from one position to the other, said C-shaped opening and the lug being so shaped and proportioned as to insure the rounded extremities of the abutments engaging only the flat sides of the lug, and the paths of movement of the lug and cam member during actuation thereof being so related that the rounded extremities of the abutments roll on the fiat sides of the lug to reduce friction to a minimum.

2. In an electric snap switch: a shallow cylindrical casing; an insulating base in the bottom of the casing; stationary contact means on the base; a contactor movable flatwise across the base to and from engagement with the stationary contact means; spring toggle means in the casing for moving the contactor to and from engagement with the stationary contacts, said spring toggle means including a cam member pivotally mounted on the base jg! oscillatory motion between limits to which the spring of the toggle connection snaps the same, a manually operable actuating means for the switch having a blade-like lug provided with opposite flat sides, said l-ug being constrained to flatwise motion in an arcuate path substantially concentric to the axis of the casin and inwardly from the cylindrical side wall of the casing; and opposed arms extending from the cam member toward the axis of the casing, said arms lying in a plane substantially perpendicular to the flat sides of the actuating lug and being soshaped as to form a reentrant recess in the cam member between the arms and being of such length that the extremity of one of the arms at all times projects into the arcuate path of the flat blade-like actuating lug to have transient engagement with a flat side thereof as said actuating means is rotated, to snap the cam member from one position to the other, and the extremities of said arms being rounded so that they roll on the flat sides of the actuating lug to reduce friction during engagement of the flat sides of the actuating lug therewith to a 3. In an electric snap switch: a movable contactor; a spring toggle for snapping the contactor from one position to another. said spring toggle including a cam member mounted to oscillate about a fixed axis between predetermined limits; a part on said cam member extending radially from its axis of oscillation, the outer edge of said part having a substantially O-shaped opening therein to provide two spaced undercut arms, one at each side edge of the opening, said arms having rounded extremities; and a flat blade-like actuating lug movable flatw-ise in an arcuate path to enter said opening so that its leading flat, side has transient engagement with the rounded extremity of one of said arms to swing the cam member from one position to another, the fixed axis of the cam member and the axis of the actua'ting lug being so related that the rounded extremities of the arms rock on the flat sides of the lug substantially throughout the entire period of engagement between the lug and arms. thereby insuring maximum ease of cam actuation.

4. In an electric snap switch: a movable contactor; a spring toggle for snapping the contactor from one position .to another; a flat bladelike switch actuating lug movable flatwise about a fixed axis in an arcuate path; said spring to gle including a cam member mounted for oscillation about a fixed pivot between predetermined limits outside the arcuate path of the switch actuating lug so that the path of the lug passes between the cam member pivot and the fixed axis of the lug; a part on said cam member projecting radially from its pivot axis, said part having a cshaped notch in its edge facing the path of the actuating lug and extending inwardly to a point adjacent to the cam member pivot; and a rounded shoulder at each end of the notch, one of said shoulders lying in the path of the blade-like actuating lug for transient engagement with a flat side thereof when the cam member is in either of its limits of oscicilation, to effect swinging the cam member from one position to the other, said C-shaped notch and the blade-like lug being so shaped and proportioned as to insure the shoulders engaging only the flat sides of the lug, and 

